The twittering of two canaries, entrapped next to two children under the rubble in a destroyed house in Bam, has led relief workers save the lives of their young pet-owners, IRNA reported.

No sooner had the relief workers started removing the debris, they came across two young children at their last gasp next to a broken cage with the two canaries.

The youngsters, seriously injured in the tremor, have been rushed to hospital in the city and are remaining in stable condition.

Relief workers also released the two canaries after saving them. Bam and its environs, home to about 200,000 people, were rattled by a strong tremor at 5:28 hours (0158 GMT) on Friday. Most of the buildings in the city are shoddily-built with mud bricks.

Some 28,000 bodies have been pulled out from the rubble four days after the earthquake, but the death toll is feared to still rise.

The Tehran Geophysics Institute put the magnitude of the quake at 6.3 degrees, while international seismological observatories recorded the tremor as strong as 6.7 degrees.

The desert city, located 1,000 kilometers southeast of capital Tehran, is home to several landmarks, including a 2000-old citadel, said to be the world's biggest mud-brick structure, which is almost gone now.